# Effects of Different Particle Sizes of Ultrafine Indica Rice Flour and Lactobacillus casei on the Fermentation and Flavor Characteristics of Danling Dongba

## TL;DR

This study shows that using ultrafine rice flour and specific Lactobacillus strains improves the flavor and quality of a traditional fermented rice product.

## Contribution

The novel contribution is optimizing ultrafine rice flour particle size and Lactobacillus strains to enhance flavor complexity in Danling Dongba.

## Key findings

- Ultrafine rice flour with 12.22 μm particle size showed best hydration and viscosity properties.
- Lactobacillus fermentation increased volatile flavor compounds from 42 to 72.
- L. plantarum enhanced fruity esters while L. paracasei enriched milk-like ketones.

## Abstract

This study aimed to enhance the flavor and quality of Danling Dongba, a traditional fermented rice product, by preparing ultrafine indica rice flours using fluidized bed airflow crushing. Flours with particle sizes of 20.16, 17.16, and 12.22 μm were fermented with
Lactobacillus plantarum
550 (
L. plantarum
550),
Lactobacillus fermentum GF1800 (
L. fermentum
GF1800), and
Lactobacillus paracasei S6 (L. paracasei
S6) under optimized conditions. The 12.22 μm flour showed the best performance, with a water absorption index of 2.32 g/g, solubility of 2.05%, swelling power of 9.26 g/g, and peak viscosity of 7632.53 cP. Solid‐phase microextraction coupled with GC × GC–MS revealed that Lactobacillus fermentation increased volatile flavor compounds from 42 (unfermented) to 72. Notably,
L. plantarum
550 enhanced fruity esters such as ethyl caprylate (1.18%), while
L. paracasei
S6 enriched milk‐like ketones such as 3‐hydroxy‐2‐butanone (1.54%). These findings demonstrate that optimizing flour fineness and Lactobacillus strains can significantly improve the flavor complexity of Danling Dongba, offering a scientific basis for its standardized production and industrial development.

This study found that ultrafine indica rice flour (12.22 μm) exhibited superior hydration properties (WAI 2.32 g/g, WSI 2.05%, SP 9.26 g/g) and higher pasting viscosity (peak viscosity 7632.53 cP). Lactobacillus fermentation increased volatile flavor compounds from 42 to 72, with
L. plantarum
550 enhancing fruity esters and
L. paracasei
S6 enriching creamy ketones. These findings provide a scientific basis for optimizing the flavor and standardizing the production of Danling Dongba.